Objectives: Crimean-Congo haemorrhagic fever (CCHF) is an acute zoonotic tick-borne viral disease caused by the CCHF virus. The virus belongs to the genus Nairovirus (family Bunyaviridae) and causes severe haemorrhagic symptoms in man with a mortality rate of 1050%. Humans are usually infected with CCHF virus either through the bite of infected ticks or by direct contact with virus contaminated tissues or blood.

Methods: From June 2000 to August 2006, sera were collected from Iranian suspected patients for CCHF and have been sent to the Arboviruses Lab (National Center) of the Pasteur Institute of Iran. The sera have been analyzed with specific ELISA for detecting antibodies (IgM and IgG), and also with RT-PCR to investigate the genome of the virus.

54.3% of the positive cases were in the age range 2140 years. The Sistan-Baluchestan province, by having 64.8% of positive cases, was the most infected province and the Isfahan province (10.4%) and Fars province (5.7%) were the second and third infected province. The most exposed professions were: Farmer (19.4%), worker (18.2%), housewife (19%) and butcher (12.5%).

Conclusion: CCHF is the most important haemorrhagic fever in most parts of Iran and confirmed cases have been found in 21 provinces of Iran. The most infected province is Sistan-Baluchistan in the southeast of Iran near the border of Pakistan and Afghanistan where the disease is endemic.

As the most involved age range are people between 2140 years old and the majority of confirmed cases professions in Iran are related to animals; such as farmer, slaughterer and butcher, so informing the high-risk groups about the transmission routes of the disease is very useful.